Centrifugal fan.



R. WARGr.l

CENTRIFUGAL FAN. APPLIoATIoN FILED AUG. 4. 19'11.

1,919,385. lPatented Mar. 5, 1912.

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ROBERT wane, or MILWAUKEE, WISCONSIN.

CENTRIFUGAL FAN.

Specification of Letters iatent.

Application filed August 4, 1911. Serial No. 642,348.

To all .whom it may concern:

Be it known that I, ROBERT WARG, a vciti- Zen of the United States, and'resident of Milwaukee, in the county of Milwaukee and State of Wisconsin, have invented certain new and useful Improvements in Centrifugal Fans; and vI do hereby declare that the following is a full, clear, and exact description thereof.

The primary object of my invention is to provide a simple and veconomically constructed centrifugal fan capable of manipulating solids without impairing its efficiency,

vsuch efficiency being due to the peculiar curvature of the fan blades. Each fan ilade is formed with a continuous conca-voconveXed face which extends throughout the length of the blade from its hub end to its' tip, the concave side being opposed to the resistance of the air with reference to rotation of the fan, whereby sudden shocks due to abrupt change of the direction of material as it is shed from the tip` ofthe fan blade is eliminated, while at the same time said blades willv freely receive and discharge solid material without snarling. Itis also preferable, in some instances, to set the curved blades tangentially with reference tc the fanv axes with the tips following in the direction of rotation, whereby shock produced by'striking the face of the blades at a right angle is avoided. In some instances I also contemplate curving or folding the edges of the blades which are disposed opposite the fancasing intake, by reason of which slight curvature or fold the :.ir is more eifectually pocketed and ma terial coming against said edge adjacent to the fan hub will b e deflected outwardly, the

rear edges of the blades being secured to a backing disk. It is also desired to form the blades with their outer and inner side edges slightly tapered or flared outwardly from the fan axis, as shown in Figure l,

the outer or intake edge o-f said blades, as previously stated, being folded.

With the above objects in view my invention consists in what is herein shown, described and claimed. y

In the drawings Fig. l represents a side elevation of a fan casing partly broken away and in section provided with a fan embodying the features of my invention; Fig. 2, a longitudinal sectional view of the same, the section being indicated .by line 2 2 of Fig. 1; Fig. 3, a-detailed cross-section of one of the blades, the section being indicated by line 3-3 of Fig. 2, and Fig. 4, a slightly modified form of one of the blades embodying the features of my invention.

Referring by'characters to the drawings l represents a fan casing having the usual circular air inlet 2 and discharge opening 3. A driven arbor 4 is axially alined with the inlet opening 2 and is journaled in bearings of a bracket 5 of any desired type, the arbor beingprovidedwith a hub 6 that is rigidly secured thereto. are arms 7 which latter are forwardly curved as shown and preferably disposed tangentially with relation to the arbor axis. Secured to the arms are fan blades 8 that are also forwardly curved from their hub en/ds to their outer tips, said curves forming gentle sweeps throughout the longitudinal area, the blades being preferably constructed from concavo-convexed plates presenting concaved faces to the force of the air, whereby said air that is received at the hub end of the fan is slightly'pocketed, but is readily shed from the peripheral edge or tip of the blades without being subjected to an abrupt angular deection that would otherwise occur were said blades straight for the `major portion of their length and there# after abruptly curved to form pockets at 'their tips. By this construction wherein ratentediuar. 5,1912.

Cast integral with the hub.

the working faces of the blades are curved scribing a sweeping curve. The outer edge of each blade which is exposed to the inrush of air and material through the casing is, as shown, provided with a forwardly curved fold 9 with the greatest degree of dish or curl above a center line with respect to the length of the blade, the flare being merged abruptly into the straight edge of the blade belowv its tip. The fold is gradually straightened out toward the bottom end of the blade,'forming a long rolling curve that is merged into the Straight edge of the blade adjacent to its lower end. Thus the folds 9 serve to further confine the air and prevent shedding at the intake edge of the fan is preferably triangular, having their intake and rear edgesy flared outwardly from the -hub axis, as shown, and the flared intake edge, as previously stated, is also folded, whereby said intake edges of the blades will,

' by centrifugal force, deect solid material outwardly that is taken in at the`\ hub of the fam-thus insuring stringv. material, which may be caught into the fan blades being Y freed therefrom. The rear flared edge of each of the fan blades is secured to a backir-.g conical disk 10 by suitable angle iron strips, whereby said fan is closed for the purpose of opposing solid material that may be drawn therein between the blades Thel fan blades, vas, shown in'Figs. l and 2, are described upon an arc of` a circle throughout their length, but, in some instances, it may be desirable to form the curvature of the blades upon an arc of an ellipse, their tips being of slightly greater curvature than the major portion of said blades I am` aware that blades have been used in fans of 4this type, which blades, for the most part, starting from the hub, presentvstraight faces in opposition to the air currents, said straight faces merging into abrupt curved tips. In this type of blade sudden shock as the material leaves the tip or face of the blades will result due to the abrupt change in the direction produced by this curvature. By curving the blade throughout its length as described, in practice it has been found that this abrupt shock is overcome, 'thetgradual' sweep producing the result. desired to be obtained, while at the same time frictional resistance is reduced I spokes extending therefrom, concavo-convex faced blades carried by the spokes, the curvature of the blades starting from the Yhub end andextending outwardly to the tips in a gradual sweep to present a continuous concaved face in la direction' of travel of the fan, the vouter` intake edges of the blades being flared' for a portion of their length outwardly from the-hub axis, and a backing i disk secured to the rear edges of said blades.

2. In a vcentrifugal fan having a easing provided with a centrally disposed intake and a peripheral discharge mouth; the combination of an arbor in axial alinement with the intake, anda spoked hub carried by the arbor a fan-blade secured to each-hub-spoke, each fan-blade being curved from its hub end to its peripheral tip to present a concave face toward the direction of rotation, the front intake edge being flared outwardly from the hub and for the most part curved forwardly, therear edge being flared in an opposite direction from thefront edge, and abacking disk secured to said rear edge.

3. In a centrifugal fan having a casingl Aprovided with a centrally ldisposed intake and a peripheral discharge mouth; the combination of an arbor in axial alinement with the* intake, and a spoked hub carried by the arbor a fan-blade secured to each hub-spoke, each fan-blade being curved` from its hub end to its peripheral tip to present a concave face toward the direction of rotation,

the front intake edge being flared outwardly from the hub axis toward the casing intake, the rear edge being iared in an opposite direction from said front intake edge, and a backing diskv secured to said rear edge.

4. In a centrifugal fan having a casing provided with a centrally disposed intake and a peripheral discharge mouth; the c ombination of an arbor in axial alinement with the intake, and a spoked hub carried lby the arbor a fan-blade secured 'to each hubspoke, each fanbladebeing curved from its vhub end to its' peripheral tip to present a Aconcave face towardy the direction of rotation, the front intake edge being provided with a forwardly ,curved fold the curvature being in the directionof travel of said fan.

In testimony that I cla-imthe foregoing I have hereunto set my hand at AMilwaukee in the county of Milwaukee and State of Wis-- consin in the presence of two witnesses.

. n ROBERT vVVARGr. 'Wit-nesses: .y j .Y MAY DowNEY,

y W. YOUNG. 

